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CDK constructs for defining an interaction between an AWS Lambda function and an AWS Step Function.

Project description

aws-lambda-stepfunctions module

---

Stability: Experimental

All classes are under active development and subject to non-backward compatible changes or removal in any future version. These are not subject to the Semantic Versioning model. This means that while you may use them, you may need to update your source code when upgrading to a newer version of this package.


Reference Documentation: https://docs.aws.amazon.com/solutions/latest/constructs/
Language Package
Python Logo Python aws_solutions_constructs.aws_lambda_stepfunctions
Typescript Logo Typescript @aws-solutions-constructs/aws-lambda-stepfunctions
Java Logo Java software.amazon.awsconstructs.services.lambdastepfunctions

This AWS Solutions Construct implements an AWS Lambda function connected to an AWS Step Functions.

Here is a minimal deployable pattern definition in Typescript:

# Example automatically generated without compilation. See https://github.com/aws/jsii/issues/826
from aws_solutions_constructs.aws_lambda_stepfunctions import LambdaToStepfunctions
import aws_cdk.aws_stepfunctions as stepfunctions

start_state = stepfunctions.Pass(stack, "StartState")

LambdaToStepfunctions(self, "LambdaToStepfunctionsPattern",
    lambda_function_props=FunctionProps(
        runtime=lambda_.Runtime.NODEJS_12_X,
        handler="index.handler",
        code=lambda_.Code.from_asset(f"{__dirname}/lambda")
    ),
    state_machine_props=StateMachineProps(
        definition=start_state
    )
)

Initializer

new LambdaToStepfunctions(scope: Construct, id: string, props: LambdaToStepfunctionsProps);

Parameters

Pattern Construct Props

Name Type Description
existingLambdaObj? lambda.Function Existing instance of Lambda Function object, providing both this and lambdaFunctionProps will cause an error.
lambdaFunctionProps? lambda.FunctionProps User provided props to override the default props for the Lambda function.
stateMachineProps sfn.StateMachineProps User provided props for the sfn.StateMachine.
createCloudWatchAlarms boolean Whether to create recommended CloudWatch alarms
logGroupProps? logs.LogGroupProps User provided props to override the default props for for the CloudWatchLogs LogGroup.
stateMachineEnvironmentVariableName? string Optional Name for the Step Functions state machine environment variable set for the producer Lambda function.
existingVpc? ec2.IVpc An optional, existing VPC into which this pattern should be deployed. When deployed in a VPC, the Lambda function will use ENIs in the VPC to access network resources and an Interface Endpoint will be created in the VPC for Amazon Step Functions. If an existing VPC is provided, the deployVpc property cannot be true. This uses ec2.IVpc to allow clients to supply VPCs that exist outside the stack using the ec2.Vpc.fromLookup() method.
vpcProps? ec2.VpcProps Optional user-provided properties to override the default properties for the new VPC. enableDnsHostnames, enableDnsSupport, natGateways and subnetConfiguration are set by the pattern, so any values for those properties supplied here will be overrriden. If deployVpc is not true then this property will be ignored.
deployVpc? boolean Whether to create a new VPC based on vpcProps into which to deploy this pattern. Setting this to true will deploy the minimal, most private VPC to run the pattern:
  • One isolated subnet in each Availability Zone used by the CDK program
  • enableDnsHostnames and enableDnsSupport will both be set to true
If this property is true then existingVpc cannot be specified. Defaults to false.

Pattern Properties

Name Type Description
lambdaFunction lambda.Function Returns an instance of the Lambda function created by the pattern.
stateMachine sfn.StateMachine Returns an instance of StateMachine created by the construct.
stateMachineLogGroup logs.ILogGroup Returns an instance of the ILogGroup created by the construct for StateMachine
cloudwatchAlarms? cloudwatch.Alarm[] Returns a list of alarms created by the construct.
vpc? ec2.IVpc Returns an interface on the VPC used by the pattern (if any). This may be a VPC created by the pattern or the VPC supplied to the pattern constructor.

Default settings

Out of the box implementation of the Construct without any override will set the following defaults:

AWS Lambda Function

  • Configure limited privilege access IAM role for Lambda function

  • Enable reusing connections with Keep-Alive for NodeJs Lambda function

  • Enable X-Ray Tracing

  • Set Environment Variables

    • (default) STATE_MACHINE_ARN
    • AWS_NODEJS_CONNECTION_REUSE_ENABLED (for Node 10.x and higher functions)

AWS Step Functions

  • Enable CloudWatch logging for API Gateway
  • Deploy best practices CloudWatch Alarms for the Step Functions

Architecture

Architecture Diagram


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